Neu
ral
Cir
cuit
s
:
Wi
ri
n
g
a
n
d
Tu
n
i
n
g
Na
ve
e
%
Ka
ur
%
F
r
i
d
a
y
,%
S
ep
t
ember%
29,%2017
%
Syn
apt
i
c
Tu
n
ing
T
hree
s
pec
if
ic
concept
s
as
s
ociat
ed
w
it
h
syn
apt
ic
tun
ing
:
v
Lo
ng
-
Te
r
m
Po
t
e
nti
a
ti
o
n
(LTP)
v
Lo
ng
-
Te
r
m
D
e
p
r
e
ssi
o
n
(LTD
)
v
Sp
i
k
e
-
Ti
m
i
ng
D
e
p
e
nd
e
n
t
Pl
a
st
i
ci
t
y
(S
TP)
Sour
c
e
LTP:
v
Hi
g
h
-f
requ
en
cy
pres
y
n
apt
ic
s
tim
u
lation,
or
v
L
ow
-f
requ
en
cy
s
tim
u
lation
w
it
h
pos
ts
y
n
apt
ic
dep
olaris
a
t
ion
.
LTD
:
v
L
ow
f
requ
ency
s
tim
u
lation
v
D
ecreas
e
in s
y
n
apt
ic
ef
fi
cacy
.
Si
gn
i
ficance
De
fi
n
i
t
ion
of
STDP
Ha
r
d
w
a
r
e
I
m
p
l
e
m
e
n
ta
tio
n
o
f
STDP
Exampl
e
“
Ne
u
r
on
s
t
h
at
fi
r
e
t
oge
the
r
wi
r
e
t
oge
t
h
e
r
.”
v
H
ebb
’
s
La
w
Syn
apt
i
c
Wi
r
ing
v
T
opographic
Maps
Ma
p
D
e
v
e
l
o
p
m
en
t
M
e
ch
an
i
sm
s
v
C
h
em
os
pecif
ic
ma
tc
h
in
g
:
•
Si
mi
l
a
ri
ty
b
etw
een
i
n
p
ut
neur
o
ns
(o
r
o
ut
p
ut
)
i
s
encoded
b
y
si
mi
l
a
ri
t
i
es
ex
p
ressed
w
i
t
h
a
mo
l
ecul
a
r
gra
dient
.
v
B
ased
off
of
Sp
erry
’
s
C
h
em
oaff
in
ity
H
y
pot
h
es
is
M
ap
De
ve
l
opm
e
n
t
M
e
ch
an
i
sm
s
v
Ac
ti
v
i
ty
-
de
pe
ndent
ma
tch
ing:
•
S
i
mi
la
ri
t
y
is
encod
ed
b
y
corre
la
t
i
on
s
i
n
activ
it
y
Ø
Co
a
c
tive
=
m
o
r
e
sim
il
a
r
H
ow
Doe
s
Th
i
s
In
for
m
at
i
on
A
ffe
ct
Ou
r
M
ode
l
?
v
Our
mode
l:
•
Ac
t
iv
it
y
-
dep
ende
nt
•
Focus
es
o
n
o
n
e
neur
o
n
a
t
a
t
i
m
e.
Sh
or
t
vs.
Lon
g-Dist
an
ce
Gu
i
dan
ce
Long
-
Di
st
an
c
e
:
v
C
h
em
otax
is
mechan
is
ms
v
St
ructural
ty
pe
mec
h
an
is
ms
Sh
o
r
t
-
Dist
a
nc
e
:
v
Sim
ilar
to
ou
r
mod
el
Con
cl
u
si
o
n
v
H
ow
do
w
e
f
in
e
tun
e
the
s
tr
en
g
th
of
our
current
model
?
1.
Axona
l
Gu
id
a
nc
e
2.
St
r
e
n
g
t
h
e
n
ing
/
weak
en
i
n
g
o
f
i
n
d
i
v
i
du
al
s
y
n
a
p
s
e
s
bas
e
d
o
n
r
e
lat
iv
e
tim
ing
o
f
pr
e
/
p
o
st
sy
na
p
ti
c
tim
i
n
g.